Magnetic memory

ABSTRACT

A magnetic memory includes: a magnetoresistance effect element having a magnetic recording layer; a first wiring extending in a first direction on or below the magnetoresistance effect element; a covering layer provided at least both sides of the first wiring, the covering layer being made of magnetic material, and the covering layer having a uniaxial anisotropy in the first direction along which a magnetization of the covering layer occurs easily; and a writing circuit configured to pass a current through the first wiring in order to record an information in the magnetic recording layer by a magnetic field generated by the current.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based upon and claims the benefit of priorityfrom the prior Japanese Patent Application No.2002-007877, filed on Jan.16, 2002; the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

[0002] This invention relates to a magnetic memory, and moreparticularly, to a large-capacity high-speed magnetic memory having theintegrated memory cells including magnetoresistance effect elements of aferromagnetic tunneling type, for example, and reduced in cross talkbetween the memory cells while making a stable read-out and write-inwith a reduced power consumption.

[0003] Magnetoresistance effect elements using magnetic films arecurrently used in magnetic heads, magnetic sensors, etc., and there is aproposal to use magnetoresistance effect elements in a solid-statemagnetic memory (magnetoresistance memory or MRAM (magnetic randomaccess memory)).

[0004] Recently, a so-called “tunneling magnetoresistance effect element(TMR element) has been proposed as a magnetoresistance effect elementconfigured to flow a current perpendicularly to the film plane in asandwich-structured film interposing a single dielectric layer betweentwo magnetic metal layers and to use the tunneling current. Sincetunneling magnetoresistance effect elements have been improved to ensure20% or higher ratio of change in magnetoresistance (J. Appl. Phys. 79,4724 (1996)), the possibility of civilian applications of MRAM isincreasing.

[0005] A tunneling magnetoresistance effect element can be obtained byfirst forming a thin Al (aluminum) layer, 0.6 nm through 2.0 nm thick,on a ferromagnetic electrode, and thereafter exposing its surface to aglow discharge of oxygen or oxygen gas to form a tunnel barrier layer ofAl₂O₃.

[0006] There is also proposed a ferromagnetic single tunneling junctionstructure in which an anti-ferromagnetic layer is provided in one of theferromagnetic layers on one side of the single ferromagnetic tunnelingjunction and the other ferromagnetic layer is used as a magneticallypinned layer (Japanese Patent Laid-Open Publication No. H10-4227).

[0007] Other type ferromagnetic tunneling junction structures, namely,one having a ferromagnetic tunneling junction via magnetic particlesdistributed in a dielectric material and one having double ferromagnetictunneling junctions (continuous film) have been proposed as well (Phys.Rev. B56(10), R5747 (1997), J. The Magnetics Society of Japan 23, 4-2,(1999), Appl. Phys. Lett. 73(19), 2829 (1998), Jpn. J. Appl. Phys. 39,L1035(2001)).

[0008] Also these ferromagnetic tunneling junctions have been improvedto ensure a ratio of magnetoresistance change from 20 to 50% and toprevent a decrease of the ratio of magnetoresistance change even upon anincrease of the voltage value applied to tunneling magnetoresistanceeffect elements to obtain a desired output voltage, and there is thepossibility of their applications to MRAM.

[0009] Magnetic recording elements using such a single ferromagnetictunneling junction or double ferromagnetic tunneling junctions arenonvolatile and have high potentials such as high write and read speednot slower than 10 nanoseconds and programmable frequency not less than10¹⁵ times. Especially, ferromagnetic double-tunneling structures ensurelarge output voltages and exhibit favorable properties as magneticrecording elements because the ratio of magnetoresistance change doesnot decrease even upon an increase of the voltage value applied totunneling magnetoresistance effect elements to obtain a desired outputvoltage value as mentioned above.

[0010] With regard to the memory cell size, however, those existingtechniques involve the problem that the size cannot be decreased belowsemiconductor DRAM (dynamic random access memory) when a 1 Tr(transistor)—1 TMR architecture (disclosed, for example, in U.S. Pat.No. 5,734,605) is employed.

[0011] For overcoming the problem, there are proposals such as adiode-type architecture in which TMR cells and diodes are seriallyconnected between bit lines and word lines (U.S. Pat. No. 5,640,343),and a simple-matrix architecture in which TMR cells are placed betweenbit lines and word lines (DE 19744095, WO 9914760).

[0012] However, in any case, the power consumption is large sincemagnetic reversal is preformed by a current magnetic field generated bya current pulse at the time of the writing, the number of integratedcells is limited since there is an allowable-current density limit ofwiring, and the area of a driver circuit becomes large since theabsolute value of write-in current may become as high as about 1 mA.

[0013] For this reason, there are many problems which should be improvedfor the conventional magnetic memories when compared with othernon-volatilized solid state memories such as FeRAM (ferroelectric randomaccess memory), a semiconductor flash memory, etc.

[0014] The solid magnetism storage in which a thin film made of amagnetic material of high permeability is provided in the surroundingsof write-in wiring is proposed (U.S. Pat. No. 5,659,499, U.S. Pat. No.5,956,267, the international patent application WO 00/10172, and U.S.Pat. No. 5,940,319).

[0015] According to such magnetic storage, since the high permeabilitymagnetism film is provided in the circumference of wiring, a currentrequired for the writing of the information on a magnetic-recordinglayer may be reduced.

[0016] However, in the magnetic storage which the U.S. Pat. No.5,659,499 discloses, the magnetic field impressed to the record layer ofa magnetoresistance effect film is uneven.

[0017] Moreover, when using the idea disclosed in the U.S. Pat. No.5,956,267 and the U.S. Pat. No. 5,940,319, it is difficult to apply amagnetic field to a free layer efficiently with the structure where thefree layer (record layer) is prepared in the central part of themagnetic layer which carried out laminating like a “dual spin valve typedouble tunnel junction.”

[0018] On the other hand, by the magnetic storage currently indicated inthe international patent application WO 00/10172, although it has thestructure where a big magnetic field can be impressed at the free layer,the manufacture becomes very difficult.

[0019] As a result of an original examination of this inventor, itbecame clear that the magnetization state of this covering layer is veryimportant when the covering layer formed in the circumference ofwrite-in wiring.

[0020] That is, when the magnetization state of a covering layer was notcontrolled, it became clear that the current magnetic field fromwrite-in wiring could not be efficiently impressed to the record layerof a magnetoresistance effect element.

[0021] Moreover, it became clear that a bad influence may arise inwriting or read-out, if an asteroid curve is deformed by a magneticinteraction between the covering layer and the adjacentmagnetoresistance effect elements depending on the direction ofmagnetization of the covering layer.

SUMMARY OF THE INVENTION

[0022] According to an embodiment of the invention, there is provided amagnetic memory comprising:

[0023] a magnetoresistance effect element having a magnetic recordinglayer;

[0024] a first wiring extending in a first direction on or below themagnetoresistance effect element;

[0025] a covering layer provided at least both sides of the firstwiring, the covering layer being made of magnetic material, and thecovering layer having a uniaxial anisotropy in the first direction alongwhich a magnetization of the covering layer occurs easily; and

[0026] a writing circuit configured to pass a current through the firstwiring in order to record an information in the magnetic recording layerby a magnetic field generated by the current.

[0027] According to another embodiment of the invention, there isprovided a magnetic memory comprising:

[0028] a first wiring extending in a first direction;

[0029] a magnetoresistance effect element provided on the first wiringand having a magnetic recording layer;

[0030] a second wiring extending in a direction across the firstdirection above the magnetoresistance effect element;

[0031] a covering layer provided on at least both sides of at least oneof the first and second wirings, the covering layer being made ofmagnetic material, and the covering layer having a uniaxial anisotropyin a lengthwise direction of the wiring on which the covering layer isprovided, along the lengthwise direction a magnetization of the coveringlayer occurring easily; and

[0032] a writing circuit configured to pass currents through the firstand second wirings in order to record one of two values of two-valuedinformation in the magnetic recording layer by magnetic fields generatedby the currents.

[0033] According to yet another embodiment of the invention, there isprovided a magnetic memory comprising:

[0034] a first wiring extending in a first direction;

[0035] a magnetoresistance effect element provided on the first wiringand having a magnetic recording layer;

[0036] a second wiring extending in a direction across the firstdirection above the magnetoresistance effect element;

[0037] a covering layer provided on at least both sides of at least oneof the first and second wirings, the covering layer being made ofmagnetic material

[0038] a conductive layer adjoining an outer side of the covering layertaken from the adjoining wiring and being made of a conductivenonmagnetic material; and

[0039] a writing circuit configured to pass currents through the firstand second wirings in order to record one of two values of two-valuedinformation in the magnetic recording layer by magnetic fields generatedby the currents.

[0040] As explained in full detail above, according to this invention,mass magnetic memory with a super-low power and low current, and withouta cross talk can be realized, and the merit on industry is great.

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be understood more fully from thedetailed description given herebelow and from the accompanying drawingsof the embodiments of the invention. However, the drawings are notintended to imply limitation of the invention to a specific embodiment,but are for explanation and understanding only.

[0042] In the drawings:

[0043]FIGS. 1A through 1C are schematic diagrams which simplify andexpress the principal part of the memory cell of the magnetic memory ofthe embodiment;

[0044]FIG. 2 is a schematic diagram showing the covering layer SM;

[0045]FIGS. 3A through 3E are cross-sectional diagrams which illustratethe wiring section which has the divided covering layer SM;

[0046]FIGS. 4A through 4D are the axial cross sectional diagrams showingthe covering layer to which the laminating of the layer which consistsof the antiferromagnetic substance is carried out;

[0047]FIG. 5 is a schematic diagram which illustrates the covering layerwhich has such the projecting section;

[0048]FIG. 6 is a schematic diagram showing the case where theprojecting section P is formed at the covering layer SM of upper wiring;

[0049]FIG. 7 is a schematic diagram showing the case where anotherprojecting section P is also formed at the covering layer SM of lowerwiring;

[0050]FIGS. 8A and 8B are schematic diagrams which illustrate change ofthe magnetic domain of a covering layer when applying a current pulsefor writing;

[0051]FIGS. 9A through 9F are conceptual diagrams which illustrate theplane forms and their magnetization direction of the recording layer RL;

[0052]FIGS. 10 and 11 are conceptual diagrams showing thecross-sectional structures of the magnetoresistance effect element ofhaving ferromagnetic single tunnel junction;

[0053]FIGS. 12 through 14 are conceptual diagrams which illustrate thecross-sectional structure of the magnetoresistance effect elements ofhaving ferromagnetic double tunnel junctions;

[0054]FIGS. 15A through 17B are schematic diagrams showing thearchitectures of the cell using a switching transistor;

[0055]FIG. 18 is a schematic diagram showing the second example of thearchitecture which can be used in the embodiment of the invention;

[0056]FIGS. 19A through 20B are schematic diagrams showing the examplesof the covering layer SM employable in the architecture of FIG. 18;

[0057]FIG. 21 is a schematic diagram showing the third example of thearchitecture where memory arrays can be stacked easily;

[0058]FIGS. 22A and 22B are schematic diagrams which illustrate thecovering layer SM provided in the architecture of FIG. 21;

[0059]FIG. 23 is a schematic diagram showing the fourth example of thearchitecture where lamination of memory arrays is easier;

[0060]FIGS. 24A through 25B are schematic diagrams showing the coveringlayer SM which can be provided in the architecture of FIG. 23;

[0061]FIG. 26 is a schematic diagram showing the fifth example of thearchitecture which can be used in the embodiment;

[0062]FIGS. 27A and 27B are schematic diagrams showing the example ofthe covering layer in the architecture of FIG. 26;

[0063]FIGS. 28 and 29 are schematic diagrams showing the furthermodified examples of the covering layer which can be used in theembodiment of the invention;

[0064]FIGS. 30 through 37 are schematic cross-sectional diagrams showingthe structure where laminating of the architectures shown in FIGS. 18through 27B is carried out;

[0065]FIGS. 38 through 41 are tables showing the results of the samplesof the embodiment and the comparative samples;

[0066]FIGS. 42 through 44 are tables showing the results of the casewhere FeMn and IrMn were added through Cu to each wirings;

[0067]FIGS. 45 and 46 are tables showing the results of the comparativesamples;

[0068]FIGS. 47 through 50 are tables showing the results of the samplesof the embodiment and the comparative samples;

[0069]FIGS. 51 and 52 are tables showing the results of comparativesamples; and

[0070]FIGS. 53 through 55 are tables showing the results of the casewhere FeMn and IrMn were added through Cu to each wirings of thesamples.

DETAILED DESCRIPTION

[0071] Some embodiments of the invention will now be explained belowwith reference to the drawings.

[0072]FIGS. 1A through 1C are schematic diagrams which simplify andexpress the principal part of the memory cell of the magnetic memory ofthe embodiment. That is, FIG. 1A is the front view showing a pair ofwrite-in wiring and the magnetoresistance effect element which arecontained in a memory cell, FIG. 1B is the plane view thereof, and FIG.1C is the side view thereof.

[0073] In the magnetic memory of the embodiment, a pair of write-inwiring BL and WL which are directed in a crossing-fashion are formed inthe upper and lower sides of the magnetoresistance effect element C. Themagnetic-recording layer whose magnetization direction can be reversedby impressing a magnetic field is provided in the magnetoresistanceeffect element C By the synthetic magnetic field produced by passingwrite-in current to a pair of write-in wiring BL and WL, respectively,the magnetization direction of this magnetic-recording layer is reversedsuitably, and “writing, i.e., information record,” is performed.

[0074] A pair of write-in wirings BL and WL have the covering layer SMon their circumferences, and the covering layer is made of a magneticmaterial. The covering layer SM is formed on the both side of thewirings and the back side seen from and the magnetoresistance effectelement C of each wiring, respectively, and has a role to preventleakage of a magnetic field from.

[0075] That is, “the write-in cross talk” to other memory cells whichadjoin in the right-and-left direction or the vertical direction by thecurrent magnetic field produced from the write-in wirings BL and WL canbe prevented by forming the covering layer SM.

[0076] Furthermore, such a covering layer SM itself becomes theso-called “magnetic yoke”. Thus, the covering layer SM guides thecurrent magnetic field produced around the write-in wirings BL and WL,and also has the effect to concentrate the magnetic field on themagnetic-recording layer of the magnetoresistance effect element C. Asthe result, write-in current is reduced and it also becomes possible tolower the power consumption of memory.

[0077] Now, in this embodiment, the magnetization easy direction M ofthe covering layer SM is formed in parallel to the lengthwise directionof the wirings BL and WL. If a uniaxial anisotropy is provided in thedirection of a long axis of the wiring in the covering layer SM, themagnetic interaction with the magnetoresistance effect element Cprovided right under or above therefrom can be made small.

[0078] As the result, the “fluctuation” in the current magnetic fieldproduced by write-in current can be suppressed, and influence of thecross talk on wiring can be made small.

[0079] If the magnetization direction of the covering layer SM is notspecified, reversal action of the magnetization direction of thecovering layer SM by the current magnetic field becomes unstable.

[0080] As a result, the write-in magnetic field impressed to themagnetic-recording layer of a magnetoresistance effect element becomesunstable.

[0081] Moreover, if the magnetization direction of the covering layer SMis suitable in the direction of the magnetoresistance effect element C,since a magnetic interaction arises, there is a possibility that anunstable phenomenon may arise in writing or read-out operation.

[0082] On the other hand, if the magnetization easy direction of thecovering layer SM is specified in the lengthwise direction of thewirings BL and WL, these problems can be solved and the stable writingand read-out will become possible.

[0083] As a material of such a covering layer SM, it is desirable to usematerials having a crystal magnetic anisotropy constant K1 not higherthan 5×10⁴ erg/cc.

[0084] Specifically, a nickel iron (nickel-Fe) alloy, a cobalt nickel(Co-nickel) alloy, or a cobalt iron nickel (Co—Fe-nickel) alloy can beused. Moreover, as the material of the covering layer SM, one of alloysincluding cobalt (Co) and at least one of zirconium, hafnium (Hf),niobium (Nb), tantalum (Ta), and titanium (Ti) can also be used(amorphous alloys can also be used).

[0085] Moreover, amorphous alloys such as (Co, Fe, nickel)—(Si, B)—(P,Al, Mo, Nb, Mn)-alloy system, metal-nonmetallic nano-granular materialssuch as (Fe, Co)—(B, Si, Hf, Zr, Sm, Ta, Al)—(F, O, N)-system, orinsulating ferrites can also be used as the material of the coveringlayer SM.

[0086] For example, by choosing suitable target composition, a Permalloy(NiFe) film having a K1 of about 2×10³erg/cc, a CoNi film having a K1 ofabout 4×10⁴erg/cc, or a CoFeNi film having a K1 of about 1×10⁴ erg/cccan be easily obtained by a sputtering process. In the embodiment, thethin film which consists of a single layer, or a laminated structure oftwo or more kinds of these films may be used for the covering layer SM.

[0087] In order to provide a uniaxial anisotropy in parallel to thelengthwise direction of the wirings BL and WL to the covering layer SMmade of such material, it is necessary to specify the form of thecovering layer SM to provide a magnetic layer thereto.

[0088] Here, as shown in FIG. 2, the sum total of the length of thecovering layer SM in alignment with the circumference of the wirings BLand WL is expressed as (2L2+L3).

[0089] And the length of the covering layer SM of the direction of along axis of the wirings BL and WL is expressed as L1.

[0090] In this case, if (2L2+L3) is made shorter than L1, a uniaxialanisotropy which met in the direction of a long axis will arise in thecovering layer SM according to the form effect.

[0091] Furthermore, when the magnetic domain size of an actually usedmagnetic material is taken into consideration, it is still moredesirable to set the sum total (2L2+L3) of the above-mentioned length ofthe covering layer SM to 1 micrometer or less. That is, if it is withinthe limits of this, it will be hard coming to generate the magnetizationof those other than the direction of a wiring length axis.

[0092] On the other hand, if the length L1 of the covering layer SM ofthe direction of a long axis of the wirings BL and WL is made notsmaller than 1.5 times of the length dl of the magnetoresistance effectelement on its longer axis, there can be substantially no influence ofthe stray magnetic field from the write-in wirings BL and WL, and astable magnetic switching property can be acquired.

[0093] Moreover, if thickness t1 and t2 of the covering layer SM is setto 0.05 micrometers or less, the anti-magnetic field in its thicknessdirection will become large, and a magnetic anisotropy which met in itsthickness direction may not be formed even at the time of annealing in amagnetic field.

[0094] As the result, influence of a magnetic interaction with themagnetoresistance effect element C of directly under or right above canbe made small, the variation in the write-in magnetic field produced bywrite-in current is suppressed, and influence of the cross talk onwiring can be made small.

[0095] On the other hand, there is a method of dividing the coveringlayer SM into plurality parts provided in the circumference of thewirings BL and WL, as another method of obtaining uniaxial anisotropy bythe form effect.

[0096]FIGS. 3A through 3E are cross-sectional diagrams which illustratethe wiring section which has the covering layer SM divided in this way.In the case of the example shown in FIG. 3A, on the both sides and theback of the wirings BL and WL, the covering layer SM is providedseparately and independently.

[0097] Thus, if the covering layer SM is divided in the direction of thecircumference of wiring, it becomes easy to make each covering layer SMinto the “long and slender” form which met in the lengthwise directionof the wirings, and thus an uniaxial anisotropy which met in thedirection of the longer axis of the wiring can be obtained easily.

[0098] In addition, since the write-in current magnetic field formed inthe wirings BL and WL is flowed back through the inside of the coveringlayer SM around the wirings BL and WL, also in the “gap” of the dividedcovering layer SM, the magnetic flux passes through from the one edge tothe adjoining edge of the covering layer SM.

[0099] Therefore, even if the covering layer SM is divided in this way,there is almost no fear of a magnetic field leaking to the circumferencefrom the “gap.” In the case of the example shown in FIG. 3B, thecovering layer SM is divided into right hand side and left hand side ofthe wirings BL and WL. Thus, since the divided covering layer SM coversthe corners of the wirings, it is more advantageous to reduce theleakage of the magnetic flux.

[0100] In the case of the example shown in FIG. 3C, the covering layerSM is divided in the side of the wirings BL and WL. Furthermore, in thecase of the example of FIG. 3D, the covering layer SM is divided also inthe back of the wirings.

[0101] In the case of the example of FIG. 3E, the barrier metal layer BMis formed on the wirings, and the covering layer SM is divide andprovided on the both sides of the wirings, and on the barrier metallayer BM separately.

[0102] As mentioned above, as illustrated in FIGS. 3A through 3E, bydividing the covering layer SM in the direction of the circumference ofthe wirings BL and WL, it becomes easy to make the covering layer SMinto “long and slender” form, and the uniaxial anisotropy which met inthe direction of the wiring length axis can be obtained certainly andeasily.

[0103] In order to fabricate the structures shown in FIGS. 3C and 3D,for example, after forming the wirings BL and WL, the covering layer SMmay be formed in order from its bottom side.

[0104] In order to fabricate the structure shown in FIG. 3E, thelaminating of the wiring and the barrier metal layer may be carried outfirst, then patterning process may be performed so that the side etchingof the wiring proceeds.

[0105] Such a side etching may be possible by choosing the materials ofthe layers and by adjusting the etching condition of RIE (reactive ionetching), for example. Thus, the both ends of the barrier metal layer BMproject outside wiring, and an overhang is formed. Then, if the coveringlayer SM is formed by methods, such as plating, the structure shown inFIG. 3E can be fabricated.

[0106] On the other hand, there is the way of carrying out thelaminating of the layer which consists of the antiferromagneticsubstance as a method of specifying the magnetization direction of thecovering layer SM.

[0107]FIGS. 4A and 4B are the conceptual diagrams showing the coveringlayer to which the laminating of the layer which consists of theantiferromagnetic substance is carried out. That is, the laminating ofthe anti-ferromagnetic layer AF is carried out to the circumference ofthe covering layer SM which consists of the magnetic substance.

[0108] Thus, by carrying out the laminating of the anti-ferromagneticlayer AF, it is possible to fix the magnetization direction of acovering layer in the direction of a wiring length axis.

[0109] In this case, the outside of the covering layer SM may be made tocarry out the laminating of the anti-ferromagnetic layer AF, as shown inFIG. 4A, or as shown in FIG. 4B, it may carry out laminating inside thecovering layer SM.

[0110] Or the anti-ferromagnetic layer AF may be inserted between thecovering layer SM.

[0111] Moreover, a non-magnetic layer may be inserted between thecovering layer SM and the anti-ferromagnetic layer AF in order to adjustmagnetic coupling with the covering layer SM and the anti-ferromagneticlayer AF.

[0112] Moreover, as illustrated in FIGS. 3A through 3E, the coveringlayer SM may be divided, and the laminating of the anti-ferromagneticlayer AF may be carried out to each of the divide parts of the coveringlayer.

[0113] By employing these structures, it becomes possible to obtain astill more stable uniaxial anisotropy.

[0114] When the anti-ferromagnetic layers AF are formed on each of apair of write-in wirings BL and WL which cross substantiallyperpendicularly each other, the process which fixes the magnetizationdirection of each anti-ferromagnetic layer AF in each direction of thewiring length axes is required.

[0115] What is necessary for that may be to use differentanti-ferromagnetic layers whose blocking temperature (temperature atwhich the coupling power between ferromagnetic/anti-ferromagneticbecomes zero) differs each other for the upper and lower wirings BL andWL, respectively.

[0116] That is, first, the magnetization direction of one of theanti-ferromagnetic layers can be fixed by cooling to a temperature lowerthan its blocking temperature during an annealing process whileimpressing a magnetic field parallel to the direction of a longer axisof the wiring on which the anti-ferromagnetic layer having a higherblocking temperature.

[0117] Then, the magnetization direction of another anti-ferromagneticlayer having the lower blocking temperature can be fixed by furthercooling to a temperature lower than the blocking temperature of theanti-ferromagnetic layer formed on another wiring, impressing a magneticfield in the parallel direction to the direction of a longer axis of thewiring.

[0118] Such a method can be performed by using two kinds ofantiferromagnetic substances whose blocking temperature differ 50degrees C. or more. As some examples of the blocking temperatures of theantiferromagnetic substances, the blocking temperature of nickelmanganese is 430 degrees C., the blocking temperature of platinummanganese is 360 degrees C., the blocking temperature of iridiummanganese is 270 degrees C., and the blocking temperature of ironmanganese is 150 degrees C.

[0119] Therefore, it is good to choose any two of these and to use forthe upper and lower wirings BL and WL, respectively.

[0120] Moreover, if a material having a crystal magnetic anisotropyconstant K1 (primary term) not higher than 5×10⁴ erg/cc is used as thematerial of the covering layer SM, a uniaxial anisotropy can becertainly obtained in the wiring directions which intersectperpendicularly, respectively, by heating more than the blockingtemperature of the anti-ferromagnetism layer AF and a ferromagneticfilm.

[0121] Further, if the conditions as explained with reference to FIG. 2are satisfied, more successful result can be achieved.

[0122] Thus, by reducing annealing temperature one by one according tothe blocking temperatures, magnetization of the covering layers SM canbe fixed in the directions of a wiring length axes about each of a pairof write-in wirings which intersect substantially perpendicularly.Moreover, it is desirable to provide a “barrier metal” which consists oftantalum nitride (TaN), silicon nitride (SiN), titanium nitride (TiN),etc. between these wirings and the covering layers SM or in the outsideof the covering layer SM.

[0123] A non-magnetic layer which consists of copper (Cu) etc. may beinserted between the covering layer SM and an anti-ferromagnetic film,in order to adjust the magnetic interaction between the covering layerSM and the anti-ferromagnetic film so that the soft magnetic propertymay be optimized.

[0124] In the above, methods to introduce the uniaxial anisotropy to thecovering layer SM has been explained.

[0125] On the other hand, in the embodiment, the electric conductivelayer which consists of copper etc. can also be provided in the outsideor inside the covering layer SM. This electric conductive layer acts asa seed layer at the time of forming the covering layer SM by methods,such as plating.

[0126]FIGS. 4C and 4D are diagrams showing the cross-sectionalstructures of the wiring which include such an electric conductivelayer. Namely, FIG. 4C shows the case where the covering layer SM isformed in the outside of the bit line BL or a word line WL, and theelectric conductive layer CL is formed in the circumference thereof.Furthermore, the barrier metal layer BM is formed in the outside of theelectric conductive layer CL.

[0127] The circumference of the barrier metal layer BM can be embeddedby the insulating layers IL, such as SiO₂. Here, the barrier metal layerBM may consist of TiN, TaN, etc., and has the role to prevent thediffusion of the materials, such as the covering layer SM, out to thecircumference.

[0128] The wiring structure shown in FIG. 4C is advantageous whenforming sequentially from the circumference. That is, a trench for thewiring is formed in the insulating layer IL, and the barrier metal layerBM is first formed in the inner wall of the trench. Then, the electricconductive layer CL is formed on the barrier metal layer BM. Theelectric conductive layer CL can be formed with copper etc.

[0129] Next, the covering layer SM which consists of the magneticsubstance can be formed by a plating method on the conductive layer CLby using the conductive layer CL as a seed layer. Finally, the wiring BL(WL) is formed by a plating method etc. inside the covering layer SM.

[0130] According to the process explained above, island growth of thecovering layer SM can be prevented by using the electric conductivelayer CL as a seed layer. That is, a thin and uniform covering layer SMcan be successfully formed by the plating method. Thus, a uniaxialanisotropy can be easily obtained by forming such thin and uniformcovering layer SM.

[0131] On the other hand, in the case of the structure shown in FIG. 4D,the barrier metal layer BM is first formed in the outside of the bitline BL or a word line WL, and the electric conductive layer CL, thecovering layer SM, and the barrier layer BB are formed in that outsidein this order. The circumference of the covering layer SM is embedded bythe insulating layer IL. The barrier layer BB can be formed by SiN etc.

[0132] The structure shown in FIG. 4D is suitable for the process formedsequentially from the inside wiring BL (WL). That is, the covering layerSM can be formed by a plating method on the surface of the electricconductive layer CL which consists of copper etc. by using theconductive layer CL as a seed layer in this case.

[0133] Also in this case, island growth of the covering layer SM can beprevented. That is, the thin and uniform covering layer SM can be formedby a plating method. Thus, a uniaxial anisotropy can be easily obtainedby forming the thin and uniform covering layer SM.

[0134] In addition, the structure of FIG. 4C is suitable for the wiringformed at the lower side of the magnetoresistance effect element C.

[0135] On the other hand, the structure of FIG. 4D is suitable for thewiring formed at the upper side of the magnetoresistance effect elementC.

[0136] In any of the cases shown in FIGS. 4C and 4D, the barrier metallayer BM and the barrier layer BB have a role to prevent a diffusion ofthe element which constitutes the covering layer SM into the insulatinglayer IL which embeds the circumference or a semiconductor deviceportion such as a MOS transistor provided in the lower part through themagnetoresistance effect element C.

[0137] In the above, the electric conductive layer CL provided in theoutside or inside the covering layer SM has been explained. On the otherhand, spin reversal with a low power and low current is furtherrealizable by adding a projecting section to the covering layers SM.Such a projecting section may be formed to project towards themagnetoresistance effect element C.

[0138]FIG. 5 is a schematic diagram which illustrates the covering layerwhich has such the projecting section. That is, as shown in this figure,the projecting section. P projected toward the direction of themagnetoresistance effect element C from the side of the write-in wiringBL and WL is formed.

[0139] If such the projecting section P is formed, the write-in magneticfield which is guided through the inside of the covering layer SM can beconcentrated on the magnetization record layer of the magnetoresistanceeffect element C. That is, the covering layer SM in the embodiment actsas “a magnetic yoke”, and guides the write-in magnetic field formed inthe circumference of the wirings BL and WL. And by forming such theprojecting section P, the emitting edge for the write-in magnetic fieldcan be made to be able to approach the magnetic-recording layer of themagnetoresistance effect element C, and the magnetic field can beapplied effectively.

[0140]FIGS. 6 and 7 are schematic diagrams which illustrate the wiringBL and WL with the covering layer SM having the projecting section P,and a relation with the magnetoresistance effect element C. That is, inthe case of the example of FIG. 6, the projecting section P is formed atthe covering layer SM of upper wiring.

[0141] And in the case of the example of FIG. 7, another projectingsection P is also formed at the covering layer SM of lower wiring. Byproviding these projecting sections at the covering layer SM like theseexamples, it becomes possible to bring the emitting edge of a write-inmagnetic field close to the magnetoresistance effect element C, andcurrent magnetic field efficiency rises while the write-in powerconsumption and the write-in current decrease.

[0142] Moreover, if write-in current is reduced in this way, sincecapacity of a drive circuit can also be made small and thickness ofwrite-in wiring can also be made thin, the size of memory will bereduced and it will also become possible to raise the degree ofintegration.

[0143] Furthermore, by decreasing the write-in current, problems, suchas electro migration in write-in wiring, can also be prevented, thereliability of magnetic memory can be raised, and a life of the memorycan also be improved.

[0144] Such a projecting section P can be provided in the case as shownin FIGS. 3A through 3E. Namely, in these structures where the coveringlayer SM is divided into some portions, the projecting section P can beprovided as well.

[0145]FIGS. 8A and 8B are schematic diagrams which illustrate change ofthe magnetic domain MD of a covering layer when applying a current pulsefor writing.

[0146]FIG. 8A is a diagram looking in a parallel direction to the bitline BL, and the FIG. 8B is a diagram looking in a parallel direction tothe word line WL. If a current pulse CP passes the write-in wiring BLand WL, a magnetic wall will be formed in the covering layer SMcorresponding to the width (it corresponds to application time) of acurrent pulse CP. And a magnetic field H is transmitted to themagnetoresistance effect element C effectively only at the place where acurrent pulse CP exists along the direction of a longer axis of thewrite-in wiring BL and WL. And the magnetic-recording layer of themagnetoresistance effect element C carries out magnetization reversal bythe write-in magnetic field which is a combination of the magneticfields H from upper and lower wirings.

[0147] As shown in FIGS. 8A and 8B, the magnetization direction of theabove-mentioned magnetoresistance effect element does not necessarilyneed to be a straight line-like, and may be crooked by forming an “edgedomain” etc. That is, the magnetization direction of amagnetic-recording layer changes to versatility according to the planeform thereof.

[0148]FIGS. 9A through 9F are conceptual diagrams which illustrate theplane forms and their magnetization direction of the recording layer RL.The recording layer RL of the magnetoresistance effect element C canhave various plane form, as illustrated in these diagrams, and themagnetization M formed there forms various “edge domains” according tothe form.

[0149] Namely, the magnetic recording layer RL may have a plane formwhere projects are added to both diagonal edges of a rectangular asshown in FIG. 9A. The magnetic recording layer RL may also have a planeform of a parallelogram as shown in FIG. 9B, a lozenge as shown in FIG.9C, an ellipse as shown in FIG. 9D, an edge inclination shape as shownin FIG. 9E or an elongated octagon as shown in FIG. 9F.

[0150] And in the case of the asymmetrical form as shown in FIGS. 9A and9B, magnetization M is crooked by formation of the edge domain insteadof the shape of a straight line. In the embodiment of the invention, itis possible to use the record layer which has the magnetization Mcrooked in this way.

[0151] Such asymmetrical form is easily produced by making the reticleused in photo lithography into asymmetrical form pattern. By forming therecording layer RL as shown in FIGS. 9A through 9F, a switching magneticfield can be reduced. According to examination of the Inventors, whenthe recording layer RL is formed as the elongated octagon as shown inFIG. 9F, it became possible to reduce the switching magnetic fieldnotably.

[0152] In addition, although the angle parts are round in fact in manycases in the form where the magnetic recording layer RL is formed intothe shapes as shown in FIGS. 9A-9C, 9E, and 9F when carrying out apatterning process. However, such rounded shape may be acceptable in theinvention.

[0153] With regard to the ratio of the length L and the width W, L/W, ofthe magnetic recording layer RL of the magnetoresistance effect elementC, it is desirable that the ratio L/W is larger than 1.2. And it is alsodesirable to give a uniaxial anisotropy in the direction of the lengthL. It is because the direction of magnetization M can be mutuallyspecified in the two directions for the contraries certainly and easily.

[0154] Next, some examples of the laminating structure of themagnetoresistance effect element C which can be used for the magneticmemory of the embodiment of the invention are explained.

[0155]FIGS. 10 and 11 are a conceptual diagrams showing thecross-sectional structures of the magnetoresistance effect element ofhaving ferromagnetic single tunnel junction. That is, in the case of themagnetoresistance effect element shown in FIG. 12, the laminating of theanti-ferromagnetic layer AF, the ferromagnetic layer FM1, the tunnelbarrier layer TB, the ferromagnetic layer FM2, and the protection layerPB is carried out to this order on the ground layer BF.

[0156] The ferromagnetic layer FM1 which adjoins the anti-ferromagneticlayer AF acts as a magnetization pinned layer (pinned layer), and theferromagnetic layer FM2 which is stacked on the tunnel barrier layer TBacts as a record layer (free layer).

[0157] In the case of the magnetoresistance effect element shown in FIG.13, in the upper and lower sides of the tunnel barrier layer TB, thestacked structures SL having the ferromagnetic layer FM, thenon-magnetic layer NM, and the ferromagnetic layer FM are formed,respectively. In this case, the stacked structure SL interposed betweenthe anti-ferromagnetic layer AF and the tunnel barrier layer TB alsoacts as a magnetization pinned layer, and the stacked structure SLprovided on the tunnel barrier layer TB acts as a record layer.

[0158]FIGS. 12 through 14 are conceptual diagrams which illustrate thecross-sectional structure of the magnetoresistance effect elements ofhaving ferromagnetic double tunnel junctions. The same symbols are givento the same elements as what were mentioned with reference to FIGS. 10and 11, and detailed explanation is omitted.

[0159] In the case of the structure illustrated in FIGS. 12 through 14,the two tunnel barrier layers TB are formed, and the stacked structuresSL of the ferromagnetic layer FM, or the ferromagnetic layer FM and thenon-magnetism layer NM are formed in the upper and lower sides.

[0160] In the cases of the double tunnel junction element illustratedhere, the ferromagnetic layers FM which adjoin the upper and loweranti-ferromagnetism layer AF respectively act as magnetization pinnedlayers, and the ferromagnetic layer FM provided between the two tunnelbarrier layers TB acts as a record layer.

[0161] If such a double tunnel junction structure is adopted, it isadvantageous at the point which can increase the current change withrespect to the magnetization direction of a record layer.

[0162] In addition, the magnetoresistance effect element used in themagnetic memory of the invention is not limited to what was illustratedin FIGS. 10 through 14, but the so-called magnetoresistance effectelement of the “spin valve structure” to which the laminating of thefirst ferromagnetic layer, a non-magnetism layer, and the secondferromagnetic layer is carried out can also be used.

[0163] Also when either structure is adopted as a magnetic resistanceeffect element, one ferromagnetic layer can be used as a “magnetizationpinned layer” in which the magnetization direction is fixedsubstantially, and another ferromagnetic layer can be used as a“magnetic record layer” in which the magnetization direction iscontrollable by applying a magnetic field from the outside.

[0164] Moreover, the ferromagnetic layer formed to adjoin theanti-ferromagnetic layer can also be used as a record layer depending onthe read-out method, as explained in full detail below.

[0165] As the ferromagnetic material which can be used as amagnetization pinned layer in these magnetoresistance effect elements,for example, Fe (iron), Co (cobalt), nickel (nickel), or these alloys,magnetite having a large spin polarization ratio, CrO₂, or RXMnO_(3-y)(where R expresses a rare earth element, and X expresses calcium(calcium), Ba (barium), or Sr (strontium)) can be used.

[0166] Further, as the ferromagnetic material which can be used as amagnetization pinned layer in these magnetoresistance effect elements,Heusler alloys, such as NiMnSb (nickel manganese antimony), PtMnSb(platinum manganese antimony), Co₂MnGe, and CO₂MnSi, can be used.

[0167] As for the magnetization pinned layer which consists of suchmaterial, it is desirable to have unidirectional anisotropy.

[0168] With regard to the thickness of these layers, it is desirable torange between 0.1 nm and 100 nm. Furthermore, in order to prevent thesuperparamagnetizm, it is more desirable to make the thickness notsmaller than 0.4 nm.

[0169] Moreover, it is desirable to provide an anti-ferromagnetic filmnear the magnetization pinned layer in order to fix the magnetizationthereof. As such an anti-ferromagnetic film, Fe (iron)—Mn (manganese),Pt (platinum)—Mn (manganese), Pt (platinum)—Cr (chromium)—Mn(manganese), Ni (nickel)—Mn (manganese), Ir (iridium)—Mn (manganese), Os(osmium)—Mn (manganese), NiO (oxidization nickel) and Fe₂O₃ (ironoxide), or magnetic semiconductors can be mentioned.

[0170] Moreover, in these magnetic materials, non-magnetic elements suchas Ag (silver), Cu (copper), Au (gold), Al (aluminum), Mg (magnesium),Si (silicone), Bi (bismuth), Ta (tantalum), B (boron), C (carbon), O(oxygen), N (nitrogen), Pd (palladium), Pt (platinum), Zr (zirconium),Ir (iridium), W (tungsten), Mo (molybdenum), Nb (niobium), or H(hydrogen) can be added in order to adjust the magnetic properties, orother various properties, such as crystallinity, mechanical properties,and the chemical properties.

[0171] On the other hand, a stacked structure having a ferromagneticlayer and a non-magnetic layer can be used as a magnetization pinnedlayer. For example, the three-layered structure of the (ferromagneticlayer)/(nonmagnetic layer)/(ferromagnetic layer) which is illustrated inFIG. 11 etc. can be used. In this case, it is desirable to make ananti-ferromagnetic interaction work between the ferromagnetic layers onboth sides through the non-magnetic layer.

[0172] As a specific method to fix the magnetization of the magneticlayer in one direction, three-layered structure such as Co (Co—Fe)/Ru/Co(Co—Fe), Co (Co—Fe)/Ir/Co (Co—Fe), Co (Co—Fe)/Os/Co (Co—Fe) and(ferromagnetic layer)/(magnetic semiconductor nonmagneticlayer)/(magnetic semiconductor ferromagnetic layer) can be used. In thiscase, it is desirable to provide an anti-ferromagnetic layer to adjointhe three-layered structure.

[0173] As such an anti-ferromagnetic layer, Fe—Mn, Pt—Mn, Pt—Cr—Mn,Ni—Mn, Ir—Mn, NiO, Fe₂O₃ and magnetic semiconductors can be used. Byemploying this structure, magnetization of the magnetization pinnedlayer can be fixed securely, a stray field from the magnetization pinnedlayer can be reduced (or controlled), and magnetization shift can becontrolled by changing the thicknesses of the two ferromagnetic layersof the magnetization pinned layer.

[0174] On the other hand, as the material of a magnetic record layer(free layer), the same as the magnetization pinned layer can be used.For example, Fe (iron), Co (cobalt), nickel (nickel), or these alloys,magnetite having a large spin polarization ratio, CrO₂, or RXMnO_(3-y)(where R expresses a rare earth element, and X expresses calcium(calcium), Ba (barium), or Sr (strontium)) can be used. Further, as theferromagnetic material which can be used as a magnetic record layer inthese magnetoresistance effect elements, Heusler alloys, such as NiMnSb(nickel manganese antimony), PtMnSb (platinum manganese antimony),CO₂MnGe, and Co₂MnSi, can be used.

[0175] The ferromagnetic layer as the magnetic record layer made ofthese materials may desirably have a uniaxial anisotropy parallel to itsfilm plane. With regard to the thickness of these layers, it isdesirable to range between 0.1 nm and 100 nm. Furthermore, in order toprevent the superparamagnetizm, it is more desirable to make thethickness not smaller than 0.4 nm.

[0176] Alternatively, a two-layered structure of (soft magneticlayer)/(ferromagnetic layer), or a three-layered structure of(ferromagnetic layer)/(soft magnetic layer)/(ferromagnetic layer) can beused as the magnetic record layer.

[0177] By using a three-layered structure of (ferromagneticlayer)/(nonmagnetic layer)/(ferromagnetic layer), or five-layeredstructure of (ferromagnetic layer)/(nonmagnetic layer)/(ferromagneticlayer)/(nonmagnetic layer)/(ferromagnetic layer) as the record layer,and by adjusting the strength of the interaction between theferromagnetic layers, it becomes possible to suppress an increase of apower consumption even if the cell width of the record layer as thememory cell becomes sub-micron.

[0178] In the case of the five-layered structure, the intermediateferromagnetic layer may desirably be a soft magnetic layer, or aferromagnetic layer which is divided by a non-magnetic.

[0179] It is also noted that in the case of the record layer, in thesemagnetic materials, non-magnetic elements such as Ag (silver), Cu(copper), Au (gold), Al (aluminum), Mg (magnesium), Si (silicone), Bi(bismuth), Ta (tantalum), B (boron), C (carbon), O (oxygen), N(nitrogen), Pd (palladium), Pt (platinum), Zr (zirconium), Ir (iridium),W (tungsten), Mo (molybdenum), Nb (niobium), or H (hydrogen) can beadded in order to adjust the magnetic properties, or other variousproperties, such as crystallinity, mechanical properties, and thechemical properties.

[0180] On the other hand, when a TMR element is used as themagnetoresistance effect element, Al₂O₃ (aluminum oxide), SiO₂ siliconeoxide), MgO (magnesium oxide), AlN (aluminum nitride), Bi₂O₃ (bismuthoxide), MgF₂ (magnesium fluoride), CaF₂ (calcium fluoride), SrTiO₂(titanium strontium oxide), AlXO₃ (X is rare earth elements, such as La,Hf, and Er), Al—N—O (aluminum nitride oxide), a non-magneticsemiconductor (InMn, GaN, GaAs, TiO₂, Zn, Te and these doped withtransition metal), etc. can be used as the material of the tunnelbarrier layer TB prepared between a magnetization pinned layer and amagnetization record layer.

[0181] These compounds may not necessarily have a perfect stoichiometriccomposition, but may have deficiency or excess of the component elementssuch as oxygen, nitrogen and fluoride. Moreover, the insulated layer(dielectric layer) may preferably thin enough to make a tunnelingcurrent flow therethrough. The practical thickness may preferably equalto or smaller than 10 nm.

[0182] Such a magnetoresistance effect element can be formed on apredetermined substrate using the usual thin film formation means, suchas various sputtering methods, vapor-depositing method, the moleculebeam epitaxy, and CVD method.

[0183] As a substrate in this case, various kinds of substrates, such asSi (silicone), SiO₂ (oxidization silicone), Al₂O₃ (aluminum oxide),spinel, AlN (aluminum nitride), GaAs, and GaN, can be used, for example.Moreover, as a base layer of a protective layer, such as Ta (tantalum),Ti (titanium), Pt (platinum), Pd (palladium), Au (gold), Ti/Pt, Ta/Pt,Ti/Pd, Ta/Pd, Cu (copper), Al—Cu, Ru (ruthenium), Ir (iridium) and Os(osmium), GaAs, GaN, ZnO, TiO₂, etc. can be used.

[0184] Moreover, as the material of the ferromagnetic layers, elements,such as Pt and Pd, may be added into Fe, Co, Ni, or these alloys inorder to form a semi-hardmagnetic film.

[0185] In the above, the basic structure of the magnetoresistance effectelement C in the magnetic memory of the embodiment and their materialsare explained.

[0186] Next, some examples are given and explained about the cellstructure of the magnetic memory of the embodiment.

[0187]FIGS. 15A through 17B are schematic diagrams showing thearchitecture of the cell using a switching transistor. That is, FIGS.15A, 16A and 17A are diagrams looking in a perpendicular direction tothe bit line BL, and FIGS. 15B, 16B and 17B are diagrams looking in aperpendicular direction to the word line WL.

[0188] When MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor)is used as a switching transistor, read-out is performed by turning thelower selection transistor T on, and by flowing a sense current in thebit line BL through the magnetoresistance effect element C.

[0189] On the other hand, writing is performed by using the bit line BLand word line WL which intersect perpendicularly. And the covering layerSM to which a uniaxial anisotropy is added as mentioned above withreference to FIGS. 1A through 8B is provided on these bit line BL andthe word line WL.

[0190] In the case of the example shown in FIGS. 16A and 16B, theprojecting section P is added to the covering layer SM for both the bitline BL and a word line WL. Therefore, the edge of the covering layer SMbecomes closer to the magnetoresistance effect element C, and write-incan be performed with a lower power and lower current.

[0191] In the case of the example shown in FIGS. 17A and 17B, theprojecting section P of the covering layer SM is divided, and providedseparately from the main part. That is, the projecting section Pdissociates from the main part of the covering layer SM on the bit lineBL, and is formed at the side of the bit line RBL for read-out connectedto the magnetoresistance effect element C.

[0192] The length of the covering layer in a direction of thecircumference of the bit line BL tends to become longer if theprojecting section P is added without a gap.

[0193] On the other hand, a uniaxial anisotropy can be more easilyobtained by a form effect, by providing the projecting section Pseparately like this example. In order to realize further super-largescale-integrated memory, it is desirable to employ a multilayeredarchitecture which can laminate memory arrays.

[0194] Next explained is some architectures where lamination of thememory arrays is easy.

[0195]FIG. 18 is a schematic diagram showing the second example of thearchitecture which can be used in the embodiment. That is, this figureshows the cross-sectional structure of a memory array. In the case ofthis architecture, the magnetoresistance effect elements C are connectedto read-out/write-in bit line BL in parallel through Diodes D. Andread-out/write-in word lines WL are connected to the other edges of eachmagnetoresistance effect elements C.

[0196] At the time of read-out, the bit line BL and word line WL whichare connected to the target magnetoresistance effect element C arechosen with the selection transistor ST, and a sense amplifier SAdetects current at the element C.

[0197] On the other hand, at the time of writing, the bit line BL andword line WL which are connected to the target magnetoresistance effectelement C are also chosen with the selection transistor ST, and write-incurrent is passed through them. In this case, the magnetic fieldsgenerated respectively by the bit line BL and the word line WL arecombined to form the synthetic write-in magnetic field. And writing isattained by the synthetic magnetic field by turning magnetization of amagnetic-recording layer in the predetermined direction.

[0198] Diode D has a role to intercept the detour current which flowsthrough other magnetoresistance effect elements C currently wired in amatrix at the time of these read-out or writing.

[0199]FIGS. 19A through 20B are schematic diagrams showing the examplesof the covering layer SM employable in the architecture of FIG. 18. Inthese drawings, in order to simplify the example, only the bit line BL,the magnetoresistance effect element C, Diode D, and the word line WLare expressed, and elements other than these are omitted.

[0200] In the memory cell of these examples, writing is performed usingthe bit line BL and word line WL which intersect perpendicularly. Thecovering layer SM mentioned above with regard to FIGS. 1A through 8B isformed on the bit line BL and a word line WL, and the projecting sectionP is further formed.

[0201] In the case of the example of FIG. 20, the projecting section Pis provided apart from the main part of the covering layer SM so thatthe section P comes in the side of Diode D, therefore a uniaxialanisotropy can be obtained more certainly.

[0202] The following methods can be used as the formation method of suchthe projection section P. That is, Diode D is formed first. Then, aninsulating layer is deposited on the upper surface and side thereof, anda material of the projecting section P is deposited on the insulatinglayer. Then, the insulating layer and the material of the projectingsection P is removed on the diode D by a polishing process such as CMP.Next, the third example of architecture employable as the magneticmemory according the embodiment is explained.

[0203]FIG. 21 is a schematic diagram showing the third example of thearchitecture where memory arrays can be stacked easily. That is, thisfigure expresses the cross-sectional structure of a memory array. Inthis architecture, a configuration of a “ladder type” is employed wheretwo or more magnetoresistance effect elements C are connected inparallel between read-out/write-in bit line BL and the bit line Br forread-out.

[0204] Write-in word lines WL are provided near each magnetoresistanceeffect element C and are provided in a direction to intersect the bitlines. The writing to a magnetoresistance effect element can beperformed by generating magnetic fields by passing current through theread-out/write-in bit line BL, and by passing current through thewrite-in word line WL, and thus a synthetic magnetic field is applied tothe magnetic-recording layer of the magnetoresistance effect element C.On the other hand, in the case of read-out, a voltage is applied betweenthe bit lines BL and Br.

[0205] Then, current flows for all the magnetoresistance effect elementsC connected in parallel among these. While a sense amplifier SA detectsthe sum total of this current, a write-in current is passed through theword line WL close to the target magnetoresistance effect element sothat the magnetization of the magnetic-recording layer of the targetmagnetoresistance effect element is rewritten in the predetermineddirection.

[0206] A read-out of the target magnetoresistance effect element can beperformed by detecting the change in the sense current at this rewritingprocess. That is, if the magnetization direction before the rewritingprocess is same as the magnetization direction after the rewritingprocess, the current detected by the sense amplifier SA will not change.However, if the magnetization direction before the rewriting process isdifferent from the magnetization direction after the rewriting process,the current detected by the sense amplifier SA changes by amagnetoresistance effect.

[0207] Thus, it becomes possible to read the magnetization direction ofa magnetic-recording layer before the rewriting process, i.e., storeddata. However, this method corresponds to so-called “destructivereading” by which storing data are changed at the time of read-out.

[0208] On the other hand, when the magnetoresistance effect element ismade to have a structure of a magnetization free layer/insulating layer(non-magnetic layer)/magnetic-recording layer, the so-called“nondestructive readout” is possible. That is, when using themagnetoresistance effect element of this structure, the write-in isperformed by recording the magnetization direction on themagnetic-recording layer, and the read-out is performed by comparing thesense current while changing the magnetization direction of amagnetization free layer suitably. In this way, the magnetizationdirection of the magnetic-recording layer can be read-out withoutchanging it.

[0209] However, in this case, it is necessary to design so that the wayof the magnetization reversal magnetic field of a magnetization freelayer may become smaller compared to the magnetization reversal magneticfield of the magnetic-recording layer.

[0210]FIGS. 22A and 22B are schematic diagrams which illustrate thecovering layer SM provided in the architecture of FIG. 21. Here, inorder to simplify the example, only the bit line BL, themagnetoresistance effect element C, and the word line WL are expressed,and elements other than these are omitted.

[0211] Also in the example shown in FIGS. 22A and 22B, writing isperformed using the bit line BL and word line WL which intersectperpendicularly. And by forming the covering layer SM in these lines, awrite-in cross talk can be reduced, and writing process can be performedwith a lower power and lower current.

[0212] Next, the fourth example of architecture employable as themagnetic memory of the embodiment is explained.

[0213]FIG. 23 is a schematic diagram showing the fourth example of thearchitecture where lamination of memory arrays is easier. That is, thisfigure expresses the cross-sectional structure of a memory array. Inthis architecture, two or more magnetoresistance effect elements C areconnected to read-out/write-in bit line BL in parallel, and the bitlines Br for read-out are connected to the other edges of thesemagnetoresistance effect elements in the shape of a matrix,respectively.

[0214] Furthermore, the word lines WL for writing are wired near the bitlines B. The writing to a magnetoresistance effect element can beperformed by making the synthetic magnetic field of the magnetic fieldgenerated by passing current through the bit line BL and the magneticfield generated by passing current through the word line WL, and thusapplying the synthetic magnetic field to the magnetic-recording layer ofthe magnetoresistance effect element C.

[0215] On the other hand, in the case of read-out, by choosing the bitlines BL and Br with the selection transistor ST, sense current can bepassed for the target magnetoresistance effect element, and the sensecurrent is detected by the sense amplifier SA.

[0216]FIGS. 24A through 25B are schematic diagrams showing the coveringlayer SM which can be provided in the architecture of FIG. 23. That is,FIGS. 24A and 25A are diagrams looking in a parallel direction to thebit line BL, and FIGS. 24B and 25B are diagrams looking from in aparallel direction to the word line WL.

[0217]FIGS. 24A through 25B express the state where the verticalrelation was reversed with regard to FIG. 23. Also in these drawings,only the bit lines BL and Br, the magnetoresistance effect element C,and the word line WL are expressed, and elements other than these areomitted for simplification.

[0218] As shown in FIGS. 24A and 24B, the covering layer SM which has auniaxial anisotropy is formed on the bit line BL and a word line WL, andthe projecting section P is further formed for the word line.

[0219] By employing such a structure, a cross talk can be reduced andwrite-in can be performed with a lower power and lower current.Moreover, in the case of the example shown in FIGS. 25A and 25B, theprojecting section P is provided separately for the word line WL. Thatis, with the covering layer SM prepared in the circumference of a wordline WL, this projecting section P dissociates and is formed in the sideof the bit line Br. Thus, it becomes easy to produce a uniaxialanisotropy by a form effect.

[0220] Next, the fifth example of architecture employable as themagnetic memory of the embodiment is explained.

[0221]FIG. 26 is a schematic diagram showing the fifth example of thearchitecture which can be used in the embodiment. That is, this figureexpresses the cross-sectional structure of a memory array. In the caseof this example, the bit lines Br for read-out are connected to themagnetoresistance effect elements C through leads L, and the word linesWL for writing are wired directly under the magnetoresistance effectelements.

[0222]FIGS. 27A and 27B are schematic diagrams showing the example ofthe covering layer in the architecture of FIG. 26. Also in this figure,only the bit line BL, the magnetoresistance effect element C, and theword line WL are expressed, and elements other than these are omittedfor simplification.

[0223] Thus, by forming the covering layer SM which has a uniaxialanisotropy to the bit line BL and a word line WL, a write-in cross talkcan be reduced, writing and read-out operation becomes stable, andwriting can be performed with a lower power and lower current.

[0224]FIGS. 28 and 29 are schematic diagrams showing the furthermodified example of the covering layer which can be used in theembodiment. That is, as illustrated in these drawings, themagnetoresistance effect element C is embedded with Insulator IN, andthe covering layer SM is formed to cover both sides of the element C.

[0225]FIGS. 30 through 37 are schematic cross-sectional diagrams showingthe structure where laminating of the architectures shown in FIGS. 18through 27B is carried out. The same sign is given to the same elementas what was mentioned above with regard to FIGS. 1A through 29 aboutthese figures, and detailed explanation is omitted.

[0226] First, FIGS. 30 and 31 show the structures where the laminatingof the architectures mentioned above about FIG. 18 through 20B iscarried out. In the case of the example of FIG. 30, since the write-inword line WL is used in common to the magnetoresistance effect elementsC1 and C2 of the upper and lower sides, the covering layer SM is formedonly in the sides thereof.

[0227] Also in this case, a stable recording and reproduction can bepossible by giving the uniaxial anisotropy to the covering layer SM inthe lengthwise direction of the wiring.

[0228] On the other hand, in the case of the example shown in FIG. 31,the covering layer SM is inserted in the word line WL. This coveringlayer SM intercepts the write-in magnetic field generated from the upperand lower bit lines BL, and has the role to controls the write-in crosstalk between the upper and lower cells.

[0229] Moreover, when this covering layer SM is formed with aninsulator, it is also becomes possible to use the upper part and thelower part of the word line WL independently.

[0230] Next, FIGS. 32 and 33 show the structures where the laminating ofthe architecture mentioned above with regard to FIGS. 21 through 22B iscarried out. In the case of the example of FIG. 32, since the write-inword line WL is used in common to the magnetoresistance effect elementsC1 and C2 of the upper and lower sides, the covering layer SM is formedonly in the sides. Also in this case, it becomes possible to perform astable recording and reproducing by giving the uniaxial anisotropy ofthe lengthwise direction of the wiring to the covering layer SM.

[0231] On the other hand, in the case of the example shown in FIG. 33,the covering layer SM is inserted in the word line WL. This coveringlayer SM intercepts the write-in magnetic field generated from the upperand lower bit lines BL, and has the role to reduce the write-in crosstalk between the upper and lower sides thereof.

[0232] Moreover, when this covering layer SM is formed with aninsulator, it is also possible to use these upper part and the lowerpart of the word line WL independently.

[0233] Next, FIGS. 34 and 35 show the structure where the laminating ofthe architecture mentioned above with regard to FIGS. 23 through 24B iscarried out. In the case of the example of FIG. 34, since the write-inword lines WL are used in common to the magnetoresistance effectelements C1 and C2 of the upper and lower sides, the covering layer SMis formed only in the sides.

[0234] Also in this case, it becomes possible to perform a stablerecording and reproducing by giving the uniaxial anisotropy of thelengthwise direction of the wiring to the covering layer SM.

[0235] On the other hand, in the case of the example shown in FIG. 35,the covering layer SM is inserted in the word line WL. This coveringlayer SM intercepts the write-in magnetic field generated from the upperand lower bit lines BL, and has the role to reduce the write-in crosstalk between the upper and lower sides thereof.

[0236] Moreover, when this covering layer SM is formed with aninsulator, it is also possible to use these upper part and the lowerpart of the word line WL independently.

[0237] Next, FIGS. 36 and 37 show the structure where the laminating ofthe architecture mentioned above with regard to FIGS. 26 through 27B iscarried out. In the case of the example of FIG. 36, since the write-inword lines WL are used in common to the magnetoresistance effectelements C1 and C2 of the upper and lower sides, the covering layer SMis formed only in the sides.

[0238] Also in this case, it becomes possible to perform a stablerecording and reproducing by giving the uniaxial anisotropy of thelengthwise direction of the wiring to the covering layer SM. On theother hand, in the case of the example shown in FIG. 37, the coveringlayer SM is inserted in the word line WL. This covering layer SMintercepts the write-in magnetic field generated from the upper andlower bit lines BL, and has the role to reduce the write-in cross talkbetween the upper and lower sides thereof.

[0239] Moreover, when this covering layer SM is formed with aninsulator, it is also possible to use these upper part and the lowerpart of the word line WL independently.

[0240] As mentioned above, the further large scale-integration becomespossible, by employing the laminating type structure as illustrated inFIGS. 30 through 37. Moreover, in the case of these laminatedstructures, the same effect can be attained as mentioned above withregard to FIGS. 1A through 8B according to the embodiment.

EXAMPLES

[0241] Hereafter, some of the embodiment of the invention will beexplained in greater detail referring to some examples.

First Example

[0242] First, as a first example of the invention, a magnetic memorywhich has 10×10 TMR cells was fabricated on the basis of the memoryarray of the simple matrix structure shown in FIGS. 23 through 24B alongwith some comparative structures. It will be as the following if thestructure of this magnetic memory is explained along with themanufacture procedure.

[0243] First, on a substrate which is not illustrated, the lower bitline BL was formed with the covering layer SM which consists of nickeliron (NiFe) formed by a plating method. Here, the main part of thewiring was made into the electric conductive layer with a thickness of 1micrometer made of copper (Cu). After that, an insulating layer wasformed by a CVD method, then CMP (Chemical Mechanical Polishing) wasperformed to obtain a flat surface. Then, the laminating structure ofTMR which has a ferromagnetic double tunnel junction was deposited by asputtering method.

[0244] The material and the thickness of each layer from the lower sideare as the following:

[0245] Ta (30 nm)/Ru (3 nm)/Ir-Mn (8 nm)/CoFe (3 nm)/Ru (1 nm)/CoFe (3nm)/AlOx (1 nm)/CoFeNi (2 nm)/Cu (1.5 nm)/CoFeNi (2 nm)/AlOx (1 nm)/CoFe(3 nm)/Ru (1 nm)/CoFe (3 nm)/IrMn (8 nm)/Ta (9 nm)/Ru (30 nm).

[0246] Next, isolated patterns of TMR elements were produced by etchingthe laminating structure to the lower Ru/Ta wiring layer by RIE(Reactive Ion Etching) using the etching gas of a chlorine system, andby using the top Ru layer as a hard mask.

[0247] Then, after depositing SiOx by the low-temperature TEOS (tetraethyl ortho silicate) process as an insulator and polishing the surfaceby CMP, the read-out bit line Br was formed by deposition and patterningprocess.

[0248] Then, after forming an interlayer insulation film by the similarmethod and performing a planarizing process, the word line WL was formedand the covering layer SM was further formed thereon by a platingmethod.

[0249] In this example, thickness of the covering layer SM was set to0.01 micrometers-0.06 micrometers. And the length of the shorter axis ofa TMR element was set to 0.25 micrometers, and length of the longer axisof the TMR was made to change in the range of 0.3 micrometers-0.8micrometers. Moreover, the length of L3 (expressed by FIG. 2) was madeinto a length of +0.15 micrometers to the length of TMR.

[0250] One example to fabricate the projecting section P which projectsbelow the wiring WL is as follows:

[0251] That is, after forming the wiring WL, trenches may be formed inthe insulated layer at the both sides of the wiring WL, then metal seedlayer may be deposited on the inner wall of the trench by a sputtering,and finally the projecting section P may be formed on the seed layer toembed the trench by a plating method.

[0252] In this example, samples where the length L1 (shown in FIG. 2) ofthe covering layer SM of the upper word line WL and the lower word lineWL was changed by within the range from the length of the longer axis ofTMR to 2.0 micrometers were produced.

[0253] When L1 is 2.0 micrometers, the adjoining covering layers SM areconnected completely and they are unified. The length L2 (shown in FIG.2) of the perpendicular direction of the covering layer SM of the wordline WL was set to 0.2 micrometers.

[0254] Then, the samples were introduced into the heat treatment furnacewhich can apply a magnetic field, thus a uniaxial anisotropy wasintroduced into the magnetic-recording layer of a TMR element, andunidirectional anisotropy was introduced into the magnetic pinned layer.Since the materials (nickel iron, cobalt iron nickel, or cobalt nickel)having the crystal magnetic anisotropy constant K1 (primary term) nothigher than 5×10⁴ erg/cc were used as the materials of the coveringlayer SM, a uniaxial anisotropy was successfully obtained by theannealing condition for the TMR element (for example, 7000 gauss, 300degrees C., 1 hour).

[0255] Thus, using the magnetic memories of this example, the TMR signaloutput after writing in 10 times was measured, the “1” levels and “0”levels of a TMR element were reversed by the checkered flag pattern,then existence of defect of operation was investigated. At that time,current value and pulse width of a write-in current pulse were optimizedso that a cross talk becomes smallest.

[0256] These results are shown in FIG. 38 through 41 as tables. Theseresults show that a defect of operation is not observed when the crystalmagnetic anisotropy constant K1 (primary term) of the material of thecovering layer SM is not higher than 5×10⁴ erg/cc, since a uniaxialanisotropy is introduced thereto by a form effect, and good results areacquired. Here, L2 is set to 0.2 microns for all samples.

[0257] That is, this example shows that there is no defect of operation,when the thickness of a magnetic covering layer is thinner than 0.06micrometers, and especially when L1>1 micrometer□ (2L2+L3).

[0258] Moreover, the results of the case where FeMn (thickness of 8 nm)and IrMn (thickness of 4 nm) were added through Cu (thickness of 0.5 nm)to each wirings of the above-mentioned samples are shown in FIGS. 42through 44 as tables.

[0259] It turned out that when an anti-ferromagnetic film is given, adefect of operation decreases remarkably and a more desirable effect isacquired as compared with FIGS. 38 through 41.

[0260] Moreover, as an example of comparison, the Inventors made themagnetic memories using the cobalt iron alloy (Co90Fe10) whose crystalmagnetic anisotropy constant K1 (primary term) is 1×10⁵ erg/cc as amaterial of the covering layer SM, and investigated the operationthereof.

[0261]FIGS. 45 and 46 are tables showing the results of this example ofcomparison. Also in the structures where a defect of operation was notseen in FIGS. 40 and 41, the defect of operation has occurred in FIG. 45and FIG. 46. Thus, when the materials having the crystal magneticanisotropy constant K1 (primary term) of 1×10⁵ erg/cc, it turns out thata uniaxial anisotropy due to a form effect becomes unstable in thecovering layer SM, and operation becomes poor.

Second Example

[0262] Next, as a second example of the invention, a magnetic memorywhich has 10×10 TMR cells was fabricated on the basis of the memoryarray of the simple matrix structure shown in FIGS. 26 through 27B alongwith some comparative structures.

[0263] It will be as the following if the structure of this magneticmemory is explained along with the manufacture procedure.

[0264] First, on a substrate which is not illustrated, the lower bitline BL was formed with the covering layer SM which consists of nickeliron (NiFe) formed by a plating method. Here, the main part of thewiring was made into the electric conductive layer with a thickness of 1micrometer made of copper (Cu).

[0265] After that, an insulating layer was formed by a CVD method, viaholes were formed therethrogh, tungsten electrodes were embedded inthese via holes, then CMP (Chemical Mechanical Polishing) was performedto obtain a flat surface.

[0266] Then, the laminating structure of TMR which has a contact wiringMx and a ferromagnetic double tunnel junction was deposited by asputtering method.

[0267] The material and the thickness of each layer from the lower sideare as the following:

[0268] Ta (30 nm)/Ru (3 nm)/Pt-Mn (12 nm)/CoFe (3 nm)/Ru (3 nm)/AlOx (1nm)/CoFeNi (2 nm)/Ru (1.5 nm)/CoFeNi (2 nm)/AlOx (1 nm)/CoFe (3 nm)/Ru(1 nm)/CoFe (3 nm)/Pt—Mn (12 nm)/Ta (9 nm)/Ru (30 nm).

[0269] Next, isolated patterns of TMR elements were produced by etchingthe laminating structure to the lower Ru/Ta wiring layer by RIE(Reactive Ion Etching) using the etching gas of a chlorine system, andby using the top Ru layer as a hard mask.

[0270] Then, after depositing SiOx by the low-temperature TEOS (tetraethyl ortho silicate) process as an insulator and polishing the surfaceby CMP, the read-out bit line Br was formed by deposition and patterningprocess.

[0271] Then, after forming an interlayer insulation film by the similarmethod and performing a planarizing process, the word line WL was formedand the covering layer SM was further formed thereon by a platingmethod.

[0272] In this example, thickness of the covering layer SM was set to0.01 micrometers-0.06 micrometers. And the length of the shorter axis ofa TMR element was set to 0.25 micrometers, and length of the longer axisof the TMR was made to change in the range of 0.3 micrometers-0.8micrometers.

[0273] Moreover, the length of L3 (expressed by FIG. 2) was made into alength of plus 0.15 micrometers to the length of TMR.

[0274] In this example, samples where the length L1 (shown in FIG. 2) ofthe covering layer SM of the upper word line WL and the lower word lineWL was changed by within the range from the length of the longer axis ofTMR to 2.0 micrometers were produced.

[0275] When L1 is 2.0 micrometers, the adjoining covering layers SM areconnected completely and they are unified. The length L2 (shown in FIG.2) of the perpendicular direction of the covering layer SM of the wordline WL was set to 0.2 micrometers.

[0276] Then, the samples were introduced into the heat treatment furnacewhich can apply a magnetic field, thus a uniaxial anisotropy wasintroduced into the magnetic-recording layer of a TMR element, andunidirectional anisotropy was introduced into the magnetic pinned layer.

[0277] Thus, using the magnetic memories of this example, the TMR signaloutput after writing in 10 times was measured, the “1” levels and “0”levels of a TMR element were reversed by the checkered flag pattern,then existence of defect of operation was investigated. At that time,current value and pulse width of a write-in current pulse were optimizedso that a cross talk becomes smallest.

[0278] These results are shown in FIG. 47 through 50 as tables. Theseresults show that a defect of operation is not observed when theuniaxial anisotropy is introduced in the covering layer SM by a formeffect, and good results are acquired.

[0279] That is, this example shows that there is no defect of operation,when the thickness of a magnetic covering layer is thinner than 0.06micrometers, and especially when L1>1 micrometer□ (2L2+L3). Here, L2 isset to 0.2 microns for all samples.

[0280] Moreover, as an example of comparison, the Inventors made themagnetic memories using the cobalt iron alloy (Co₉₀Fe₁₀) whose crystalmagnetic anisotropy constant K1 (primary term) is 1×10⁵ erg/cc as amaterial of the covering layer SM, and investigated the operationthereof.

[0281]FIGS. 51 and 52 are tables showing the results of this example ofcomparison. Also in the structures where a defect of operation was notseen in FIGS. 49 and 50, the defect of operation has occurred in FIG. 51and FIG. 52. Thus, when the materials having the crystal magneticanisotropy constant K1 (primary term) of 1×10⁵ erg/cc, it turns out thata uniaxial anisotropy due to a form effect becomes unstable in thecovering layer SM, and operation becomes poor.

[0282] Moreover, the results of the case where FeMn (thickness of 6 nm)and IrMn (thickness of 5 nm) were added through Cu (thickness of 0.7 nm)to each wirings of the above-mentioned samples are shown in FIGS. 53through 55 as tables. It turned out that when an anti-ferromagnetic filmis given, a defect of operation decreases remarkably and a moredesirable effect is acquired.

[0283] Heretofore, some embodiments of the invention have been explainedwith reference to specific examples. The invention, however, is notlimited to these specific examples. For example, the inventioncontemplates in its own cope all alternatives concerning materials,thicknesses, shapes, sizes, etc. of the covering layer, wirings,ferromagnetic layer, insulating film, anti-ferromagnetic layer,nonmagnetic metal layer, electrode that are components of the switchingelements and/or magnetoresistance effect element as far as personsskilled in the art can appropriately select them and can practically usethe invention to obtain substantially the same effects.

[0284] Similarly, the invention contemplates in its own scope allalternatives concerning structures, materials, shapes and sizes of thebit line, digit line, word line, overcoat layer, selection transistor,diode and other composing the magnetic memory according to anyembodiment of the invention as far as persons skilled in the art canappropriately select them and can practically use the invention toobtain substantially the same effects.

[0285] Further, the invention contemplates in its scope all magneticheads including a lateral recording head and a vertical recording headthat persons skilled in the art can make by modifying the magneticmemories shown here as embodiments of the invention.

[0286] Furthermore, the invention contemplates in its scope all magneticmemories that persons skilled in the art can make by modifying themagnetic memories shown here as embodiments of the invention.

[0287] While the present invention has been disclosed in terms of theembodiment in order to facilitate better understanding thereof, itshould be appreciated that the invention can be embodied in various wayswithout departing from the principle of the invention. Therefore, theinvention should be understood to include all possible embodiments andmodification to the shown embodiments which can be embodied withoutdeparting from the principle of the invention as set forth in theappended claims.

What is claimed is:
 1. A magnetic memory comprising: a magnetoresistanceeffect element having a magnetic recording layer; a first wiringextending in a first direction on or below the magnetoresistance effectelement; a covering layer provided at least both sides of the firstwiring, the covering layer being made of magnetic material, and thecovering layer having a uniaxial anisotropy in the first direction alongwhich a magnetization of the covering layer occurs easily; and a writingcircuit configured to pass a current through the first wiring in orderto record an information in the magnetic recording layer by a magneticfield generated by the current.
 2. A magnetic memory according to claim1, wherein a total length of the covering layer along a circumferencedirection of the first wiring is equal to or smaller than onemicrometer.
 3. A magnetic memory according to claim 1, wherein athickness of the covering layer is equal to or smaller than 0.05micrometer.
 4. A magnetic memory according to claim 1, wherein thecovering layer is divided into a plurality of parts, the parts beingparallel to each other and extending in the first direction.
 5. Amagnetic memory according to claim 1, wherein a layer made of anantiferromagnetic material is laminated with the covering layer.
 6. Amagnetic memory according to claim 1, wherein the covering layer has aprojecting part which projects toward the magnetoresistance effectelement from the first wiring.
 7. A magnetic memory according to claim1, wherein the covering layer has a divided part which is providedseparate from a part of the covering layer adjoining the first wiring,and the divided part being provided close to the magnetoresistanceeffect element.
 8. A magnetic memory according to claim 1, wherein thecovering layer is made of a material selected from the group consistingof nickel-iron alloy, cobalt-nickel alloy, cobalt-iron-nickel alloy,alloy of cobalt and at least one of zirconium, hafnium, niobium, tantrumand titanium, amorphous alloy of a (Co, Fe, Ni)—(Si, B)—(P, Al, Mo, Nb,Mn)-system, a nano-granular metal-nonmetal material of a (Fe, Co)—(B,Si, Hf, Zr, Sm, Ta, Al)—(F, O, N)-system, and an insulative ferrite. 9.A magnetic memory according to claim 1, further comprising a conductivelayer adjoining an outer side of the covering layer taken from the firstwiring and being made of a conductive nonmagnetic material.
 10. Amagnetic memory according to claim 9, wherein the conductive nonmagneticmaterial includes copper as its main component.
 11. A magnetic memoryaccording to claim 1, wherein the covering layer is made of a magneticmaterial having a crystal magnetic anisotropy constant K1 equal to orsmaller than 5×10⁴ erg/cc.
 12. A magnetic memory comprising: a firstwiring extending in a first direction; a magnetoresistance effectelement provided on the first wiring and having a magnetic recordinglayer; a second wiring extending in a direction across the firstdirection on the magnetoresistance effect element; a covering layerprovided on at least both sides of at least one of the first and secondwirings, the covering layer being made of magnetic material, and thecovering layer having a uniaxial anisotropy in a lengthwise direction ofthe wiring on which the covering layer is provided, along the lengthwisedirection a magnetization of the covering layer occurring easily; and awriting circuit configured to pass currents through the first and secondwirings in order to record one of two values of two-valued informationin the magnetic recording layer by magnetic fields generated by thecurrents.
 13. A magnetic memory according to claim 12, wherein a totallength of the covering layer along a circumference direction of thewiring on which the covering layer is provided is equal to or smallerthan one micrometer.
 14. A magnetic memory according to claim 12,wherein a thickness of the covering layer is equal to or smaller than0.05 micrometer.
 15. A magnetic memory according to claim 12, whereinthe covering layer is divided into a plurality of parts, the parts beingparallel to each other and extending in a lengthwise direction of thewiring on which the covering layer is provided.
 16. A magnetic memoryaccording to claim 12, wherein a layer made of an antiferromagneticmaterial is laminated with the covering layer.
 17. A magnetic memoryaccording to claim 12, wherein the covering layer is provided on each ofthe first and second wirings, a first layer made of an antiferromagneticmaterial having a first blocking temperature is laminated with thecovering layer provided on the first wiring, a second layer made of anantiferromagnetic material having a second blocking temperaturedifferent from the first blocking temperature is laminated with thecovering layer provided on the second wiring
 18. A magnetic memoryaccording to claim 12, wherein the covering layer has a projecting partwhich projects toward the magnetoresistance effect element from thewiring on which the covering layer is provided.
 19. A magnetic memoryaccording to claim 12, wherein the covering layer has a divided partwhich is provided separate from a part of the covering layer adjoiningthe wiring, and the divided part being provided close to themagnetoresistance effect element.
 20. A magnetic memory according toclaim 12, wherein the covering layer is made of a material selected fromthe group consisting of nickel-iron alloy, cobalt-nickel alloy,cobalt-iron-nickel alloy, alloy of cobalt and at least one of zirconium,hafnium, niobium, tantrum and titanium, amorphous alloy of a (Co, Fe,Ni)—(Si, B)—(P, Al, Mo, Nb, Mn)-system, a nano-granular metal-nonmetalmaterial of a (Fe, Co)—(B, Si, Hf, Zr, Sm, Ta, Al)—(F, O, N)-system, andan insulative ferrite.
 21. A magnetic memory according to claim 12,wherein the covering layer is made of a magnetic material having acrystal magnetic anisotropy constant K1 equal to or smaller than 5×10⁴erg/cc.
 22. A magnetic memory according to claim 12, further comprisinga conductive layer adjoining an outer side of the covering layer takenfrom the adjoining wiring and being made of a conductive nonmagneticmaterial.
 23. A magnetic memory according to claim 22, wherein theconductive nonmagnetic material includes copper as its main component.24. A magnetic memory comprising: a first wiring extending in a firstdirection; a magnetoresistance effect element provided on the firstwiring and having a magnetic recording layer; a second wiring extendingin a direction across the first direction on the magnetoresistanceeffect element; a covering layer provided on at least both sides of atleast one of the first and second wirings, the covering layer being madeof magnetic material a conductive layer adjoining an outer side of thecovering layer taken from the adjoining wiring and being made of aconductive nonmagnetic material; and a writing circuit configured topass currents through the first and second wirings in order to recordone of two values of two-valued information in the magnetic recordinglayer by magnetic fields generated by the currents.
 25. A magneticmemory according to claim 24, wherein the conductive nonmagneticmaterial includes copper as its main component.
 26. A magnetic memoryaccording to claim 24, wherein the covering layer is made of a magneticmaterial having a crystal magnetic anisotropy constant K1 equal to orsmaller than 5×10⁴ erg/cc.
 27. A magnetic memory according to claim 24,wherein a layer made of an antiferromagnetic material is laminated withthe covering layer.